Self-balancing loadere fork



`c. w. BOPP SELF-BALANCING LOADER FORK 5 Sheets-Sheet l N .QI

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INVENTOR. C W BOPP ATTORNEY Aug. 26, 195s Filed Deo. 51,1195@V Aug. 26, 1958 c. w. BOPP vsmurf-131mm:ING LOADER FORK 3 Sheets-Sheet 2 Filed Deo 31, 1956 INVENTOR. C. W. BOPP ATTORNEY 3 Sheetrs-Sheet 5 C. W. BOPP SELF-BALANCING LOADER FORK Aug. 26, 1958 Filad Dec. 31, 1956 IJvVlsNToILA c. w. soPP ATTORNEY United States Patent SELF-BALANCING LOADER FORK Cecil W. Bopp, Waterloo, Iowa,

assignor to Bopp Mfg., Inc., Waterloo, Iowa,

This invention relates to the art of materials handling and more particularly to a suspended or otherwise supported element susceptible to unbalancing because of variations in loads or load' masses thereon, the invention having for a principal object the provision of means for automatically incurring balancing of the element when empty as well as when subjected to various loads.

The invention iinds practical' utility in the eld of handling building blocks, although the principles of the invention obviously have wider application. ln the case of building blocks, however, those familiar with the art will recognize thatthese blocks, conventionally provided with three through-apertures each, are best handled for loading and unloading by stacking the blocks in what are known as cubes, an arrangement or pattern having a bottom layer in which several rows of blocks are supported in a horizontal plane and additional blocks are carried on the bottom layerl so that a conventional cube may be, for example, three blockswide, iive or six blocks deep and tive, six or seven blocks high. When the blocks are cubed by a machine there is no interlocking of either layers or rows and hence it is possible to segregate or lift oi one or more series of blocks from the main cube, thus using only a portion of the cube in circumstances in which it is unnecessary or undesirable to handle the Whole cube at once.

In conventional practice, the cube or parts thereof is best handled by a loader fork having tines which are received in the fore-and-aft alined through apertures of the lowermost layer of blocks. If the tines are inserted compl'etely through the cube, the entire cube will be lifted; if

the insertion is only partial, with the free ends of the.

tines being stopped at a Vertical plane of separation between one upright series and the series immediately behind it, then only the front portion of the cube will be handled. However, since the fork is suspended from a boom or the like, as by means of a cable, Variations in the load masses thus .picked up will of course modify the center of balance of the loaded fork and if the fork is designed for balancing when empty and when fully loaded, this balance is destroyed when the fork is only partly loaded, and, if the tines of the loaded fork cannot maintain a horizontal position when thus partly loaded, the load is very apt to slip oif or the fork becomes otherwise unwieldy.

According to the present invention, these disadvantages are overcome by means providing a new suspension point of the fork for each variation in load. Specically, in the case of a cube six blocks deep, which thus gives the cube a front, an intermediate and a rear series of blocks, each having two transverse rows, the fork can handle a full cube, two-thirds of a cube or one-third of a cube, and will be self-balancing under any of those conditions as well .as when empty. This object is achieved by a shifting suspension means in conjunction with control means for lixing the location of the point of suspension in response to the particular load or load mass on the fork. It isa signicant object of the inveny 2,849,253 Patented Aug. 26, 1,958

tion to provide the control means `in the form of' cooperative stop means which function to. determine. the amount of penetration of the blocks or equivalent load material by the tines or other element and thus to determine not only the size but also the position of the. load mass on the fork. Further objects of the invention reside in simple and novel load stops or' controls,` means for releasably locking these stops'in retracted or operative positions, coordinatedV connections between these stopsA and ther control for the suspension means' relativeV to a, track along which the suspension means moves in responseA to 'variations in load on the fork orl equivalentelement,

means for controlling the swiveling of the' loaded' and unloaded fork, and such other features, singly and/or in combination, as will appear from the ensuing description of a preferredy embodiment of the invention as illustrated in the accompanying' sheets of drawings, the several iig'- ures of which are described immediately below.

Figure l is a rear elevation of the loader fork.

Figure 2 is a section on the line 2-2 of Figure 1.

Figure 3 is a perspective of a representative cube of blocks.

Figure 4 is an enlarged fragmentary rear view asi seen along the line 4-4 of Figure 2.

Figure 5 is a section on the line 5 5 of Figure 4', showing both load stop means retracted or idle.

Figure 6 is a View similar to Figure 5 but showing one stop meansl in its operative position.

Figure 7- shows both stops in their down or operative positions.

Figure 8 is an enlarged section asg seen along the line 8 8 ofA Figure l, showing the status oi' the suspension means when the fork is empty.A

Figure 9' is similar4 to Figure 8 but shows how` the lock on the suspensionl means is released when the, lifting force is applied.

Figures l0, 11 and 12' are reduced` schematic views showing different load masses and corresponding suspension points forthe fork.

Figure 13 is a section on the line 13-13 of Figure. 2.

Figures 14 and 15 are similar v iews but showing dife ferent positions of the track stops.

Figure 16 is a section onv the line 16-16 of; Figure 2.

Figure 17` is an enlarged section on the line lT-17 of Figure 16.

The' invention is best described in terms of its. ap plication to a tined loader fork for handling` building blocks of the character referred to; although,l the broader principles are applicable to other situations, in which loadable materialv is piled or stacked in, such manner that portions thereof are separable from the main mass substantially along selected upright planes of cleavage. Hence, such expressions as forkj blocks,." etc. are terms of convenience and not of. limitation; likewise, descriptive or locational' expressions such as front, rear top, bottom, etc., used in the specilication and' in the claims are merely relative and do not exclude constructions varying from that disclosed as, long as the basic principles. of the. invention are exploited.

The loader fork or load-handling element is designated in its entirety by the numeral 20 and is shown as comprising a rigid frame or upright back 22, having load-receiving means inthe form of a plurality of tines 24 rigidly attached to its lower end and extending outwardly or forwardly to free outer ends and an upper traclc means 216 Y rigidly joined to the upper end or part of the back 22- and extending outwardly in overhanging relation to' the tines. The fork is carried byl suspension means 28', including: a cable 30, connected to any suitable overhead means such as a boomy or the like (not shown).

Figure 3 shows a representative cube: of conventional 3. building blocks, here three blocks wide, six blocks deep and live blocks high; although, other quantities could be used. That shown is the one most commonly selected. As will be clear, the blocks, individually indicated at 32, are arranged or patterned in a lower layer 34 and four successive layers 36, 38, 40 and 42 supported one on the other, the lower layer of course being supported on the ground or yfloor and the blocks therefore lying in a cornmon horizontal plane. It will be noted that the cube may also be considered as being made up of a front series 44, an intermediate or second series 46 and a rear or third series 48, each series being three blocks wide, two blocks deep and ve blocks high. This pattern thus lends itself (as do variations thereof) to handling of the whole cube (Figure 12), two-thirds of the cube (Figure 1l) or one-third of the cube (Figure by the fork 20, depending upon the extent of penetration of the foreand-aft alined apertures 50 of the lower layer 34 by the fork tines 24. In other words, the cube is separable along the upright plane between the block series 44 and 46 or along the upright plane between the series 46 and 48, these planes being transverse to the length of the tines 24.

The present fork is designed on the basis of the cube illustrated and includes control means 52 for determining the extent of penetration of the cube by the tines 24, which control means is coordinated with'track control means 54 through interconnecting means in the form of a link or link means S6.

The block or load stop control means 52 is best shown in Figures 4 through 7, and comprises a pivot member 58 mounted transversely between a pair of members 60 of theV fork frame or back 22 and a pair of baillike elements hereinafter referred to as the long stop 62 and a short stop 64. As will be readily apparent from Figure 1, and thus requiring no further detailed description, each stop comprises a pair of elongated side members and a cross bar, and each side member of the long stop 62 is welded to a collar 66 turnable on the pivot member 58. Likewise, each side member of the short stop 64 is welded to a collar 68 also journaled on the pivot member 58. A washer 70 is welded to the pivot member to confine the collars against undesirable axial 'shifting. The collar 66 has welded thereto a radial web 72, and a smaller radial web 74 is welded to the short stop collar 68. A lug 76 is rigidly secured to one frame member 60 in spaced relation above the pivot member 58 and has a pair of vertical, laterally spaced apart apertures 78 and 80 therethrough for respectively receiving the upper ends of rods 82 and 84. The lower end of the rod 82 is pivotally connected at 86 to the web 72 for the long stop 62 and a similar pivotal connection for the rod 84 is made at 88 to the short stop collar web 74 (Figures 4 and 6). Coiled compression springs 90 and 92 respectively encircle the rods 82 and 84 and act against the bottom of the lug 76 and respectively against washers 94 and 96 that are welded to the rods. The apertures 78 and 80 in the lug 76 are sufciently large to loosely receive the upper ends of the rods 82 and 84 and thus accommodate rocking of the rods as the block stops are swung selectively between their retracted and operative positions. For example, as the short stop 64 is swung to the position of Figure 6, which is its operative position, while the long stop 62 remains in its retracted position, the pivotal connection 88 of the rod 84 to the short stop web 74 shifts over-center as respects a line drawn through the lug 76 and pivot member S8, and the spring 92 is first compressed and then extends as the change in position is made. This affords an over-center releasable locking device for selectively retaining either position of the shortstop. A similar result is achieved by the other rod 82 and spring 90 as the long stop 62 changes position.

As will be best apparent from Figures 1 and 2, the cross bar of the short stop 64 lies in front of the side members of the long stop 62, which thus elects a oneway connection between the two stops so that although the short stop 64 can be swung independently from its retracted position to its operative position, swinging of the long stop from its retracted position to its operative position entails automatic swinging of the short stop to its operative position. Likewise, the long stop must be in its retracted position before the short stop can be returned to its retracted position. In other words, when the long stop is in its down position (Figures 7 and 10), the short stop is also in its down position, although the latter does not at that time function as a block stop, its down position being but incident to the down position of the long stop. Nevertheless a significant function results with respect to operation of the track control means 54, previously referred to.

The link 56, which is part of the interconnecting means between the block and track control means, has a clevis 98 at its lower end which is slotted at 100 to receive a connecting pin 192 for connection to the short stop web 74. The upper end of the link 56 is pivotally connected to an arm 104 on a track control shaft 166 that runs lengthwise of the track means 26. Suitable bearings 108 and 110 are provided on the track means for rockably carrying this shaft. A tension spring 112 serves as means for biasing the shaft to an initial position best shown in Figures l and 13.

This shaft has adjustably fixed thereto a pair of track stops 114 and 116, selective axial adjustment of which along the shaft may be achieved as by a construction shown in Figure 17, whereat is shown a set screw 118 as representative of any suitable securing means. It should be understood that adjustment is utilized merely to set up the control for a particular fork and that once the adjustment is accomplished, the set screws are tightened and remain so until some circumstance requires alteration of the stops. The spring 112, which biases the shaft 106 to its initial position, returns the shaft to that position, at which the shaft is stopped as by engagement of the stop 116 with a lug or block 120 secured to the inside of one of the channels of the track means 26 (Figure 16). The shaft is rocked counterclockwise as seen in Figure 1 when either or both. of the block stops is swung to its down or operative position, and this determines the effectiveness of the track stops 114 or 116 as respects the location of the suspension means 28 along the track means 26.

The suspension means comprises a sheave 122 which receives the aforementioned cable 30 and which has a clevis 124 connected by swivel control means 126 to a top plate 128 of a track follower or cart 130, this cart having side members 132 welded to the plate 128 and journaling four rollers 134 which ride the undersidcs of the iianges on the track means channels. The rollers occupy the oblique positions shown because of the conventional angle on the channel flanges. The cart carries at one side of its front edge a stop 136 which is engageable with one or the other of the track stops 114 or 116 or may clear both stops and ultimately engage a third or fixed track stop 138 at the extreme outer end of the track means (Figure 16). When the fork is empty, the cart occupies its E position (Figures 2, 13 and 16) and abuts an initial stop 140 which fixes that position.

The track inclines upwardly and forwardly or outwardly and the cart 130 via its rollers 134 is capable of running uphill along the track means according to variations in load masses imposed on the tines. Normally, the cart is biased to its starting or E position by biasing means including a cable 142 connected to the cart, trained over a sheave 144 and connected by a spring 146 to the frame 22 as via the pivot member 58 (Figure l). The spring 146 will yield when the loaded fork is picked up via the cable 30 and suspension means 28 and the cart tends to run uphill on the track means according not only to the weight of the load but also` to its'locationf on the ti'nes. According tol the present invention, the'. extent of uphili travel` of the cart along the.A trackA meansI is controlled` bythe combination of the track stops- 1.1?4, 1116= and 138 and? the block stops 62r and. 64, and this in turn depends upon the amount of angular movement of the track controly shaft 106 as compelledl by the: block stops` 62 and' 64, which control the arm: 104 via the link 56l and additional meansl to be presently described.

It: was previously statedfvthat the link 56 had at its lower endl a` slotted clevis 98:v having a. pivotal connection at. '2 to the short stop.- web 7'4. Now, if the short stop: alonev is moved to its. down orv operative position (Figures` 6.1 and 1111):, the pin.- 102 is at the bottom' of the clevis slot 100 and the link 56 is pulled downwardly a limited amount to turn. the shaft 1.06 in such. amount as to` change. the. track. stop: positions from Figure 1.3 to Figurev 14. If' both block stops are moved toV their down positions, the; shaft 106 is turned7 additionally to .achieve the: track stop positions of Figure 15.v The additional turning of the shaft 106: is effected' by means of alink 148 having a:pivota1 connection 150.V to` the long stop web. Z2 andraione-way lostmotion connection tottheV long link 56,

which connection includes. a stop lug 152i rigid on the link. 56: and engageable from; above by an apertured' ear 154! on: the link. 148. When only the short block stop 64l is'` turned. down, they pin-to-clevis connection 102.*-98 is4 the: only etfective: connection to the link 56v and; the lug 152. on` the link 56 merely moves. downwardlyv free of the apertured ear 154' on the link 148 (FigureA 6). However, when, the long. block. stop: is then turned'. downwardly, the. ear' 154 now. engages the link lug 152` from above. and'ipullsfurther.` downwardly on the link 56during which. time the slot. 100: in the clevis 98 rides the` pin 102 on the. shortstop web. 7'4? (Figure 'Z1 If only the long stop is returned to its retracted position, the return spring 112y reverses the shaft 106 untilv it is stopped. when the pin 102 in the short stop' web` 74 again engages the bottom of the clevis slot 100. Although the pivotpoints 102 and 150 have the same angular range in amount a large part of the range of the point 102 is above and to the left, of the axis of the mounting pivot. 58',v whereas the point 150 is more immediately effectivey as respects they amount of downward motion transmitted to the link 56. These and further characteristics'of the mechanism will be set forth subsequently under the` heading operation The track means 26, comprising the pair of channels previously referred to, is rigidly attached to the fork frame 2v2v as by welding, which is characteristic of the entire assembly, because welding lends itself to this type of structure; however, the structure may be otherwise assembled without sacrificing the inventive advantages taught. The track means is suitably bracedV by welded braces 1561 l Another feature of the. invention is the controlled swivel connection 126 between thelsheave 122 and cart 1,30, best shown in: Figures 8 and 9. The cart plate 128 is apertured at` 158' to receive a T-headed stud 160. that is pivoted by a1 cross pinv 162 to the clevis 1124, which has apertured depending ears 166, thus alording a substantially universal connection including the horizontal axis of the pin 1162. and the vertical axis of the. stud 160, about the latter of which the clevis 1724 and sheave 12:2 may turn relative to the cart 128. Since the cart is guided by the. track, the fork and sheave 122 may swivel relative to each other about the stud 160. However, thisswivelingl is undesirable when the fork is empty, resting on the ground, for example, and the cable 30A is slack since the cable at that time. may tend to twist and very often the cable remains twisted until the fork is lifted and then unt-wists, causing undesirable spinning of the fork. To prevent thisv spinning, the means 126 inf corporates a brake or restraining device,.here taking: the Yformof' undersurface portions. 164 on the 'IT-head1 ofi. the

6 stud 160i. These surface portions cooperate with the proximate portion. of the upper surace of' the carti plate 128i and the two surfacesV are biased together` by a rela;- tively strong compression spring168: which acts between the underside of the plate 128 and a thrust bearingf1'10 which. abuts a nut.172`on.the lower end of, the stud.160`;

When. the fork is empty, the spring 168 forces the undersurfac'e 164; against the top of the cart plate4 128 to lock the swivel 126 against4 effectiveness. When. the fork is loaded and a lifting. force is applied' to ther suspension means 28, the spring is compressed and. the surfaces separate. A sleeve or ring 174 encircles. the spring; 166 and, being axially shorter than the spring 168 when. that spring is expanded (Figure 8),. serves as a limit when the aforesaid' surfaces are separated (Figure` 9)?. That is, the collar now becomes solidly confined between the thrust bearing and the bottom side of the cart plate 182 and the fork is free to swivel; whene loaded. It should be understood` that Figures 8 and 97 show the suspension means in; the same relative positionon= the track means 26, but normally theV sus-pensiony means. will have run uphill on the track when theV fork. is loaded anda. lifting force is applied to the. suspension means.

Operation ToV start with, it' will be assumed that the. fork 20 is empty and that both: block stops 62 and` 64 are in their up or retracted positions. Whether orV not the| fork. is suspended or resting on the' ground or other support, the suspension means 28, including. the cart 13.0.", will be at its empty or E position, biased thereto by the spring and cable means 146-144. Whenthe fork is lifted vi'a: the suspension means, the cart will remain at the E,I position, which has been calculated to-v accommodate the center of mass of the empty fork so that. the fork. is int balance; i. e., when it is suspended, the. tines 24 will be horizon;- tal. In such status, itis easily guided into the apertures of the cube of blocks. Since the. block: stopsl are: re.- tracted (Figure 2), the tines mayl penetrate the' cube via the apertures 50 to the maximum extent and the' entire cube will be lifted. As. the lifting. force is applied, the suspension means runs uphill on the track. means; 26 and is stopped at the full or F position (Figures 12 and 13)', since theV control' shaft 106 occupies; its initial position, to. which it is biased by the; return spring 1:12 as long as both block stops 62 and 64'4 are retracted, and the track stop 114- on the shaft is projected. intothe path of the cart stop 136 (see4 also Figure, 16). At: the same time, the swivel means 126 is released; that is, the: spring 168 is compressed and the fork is suspended from the sheave 122 and clevis 124 via the stop. ring 174 and thrust' bearing 1.70', enabling easy turning: of the' loaded fork about the swivel stud 1611? without. twisting the cable 30.

When the cart'l 1-301 stops at the: F position, the point of suspension is such that the fully' loaded. fork is again properly balanced and the tines remain` horizontal, which is important from the standpoint of easy maneuverability of the load without danger ofv same sliding oiii: the tines. When the situs of the load is-reached, the' eube'i's` lowered to the ground or other support, su'chf as the; bed of a truck, etc., and as soon as the load is relieved from the fork, the cart tends to return to its E position under action, of the spring and cable means 146-144; hence, the tines may be easily withdrawnfrom' the. cube. and the fork may be. removed to pick up another load if, desired, the swivel means again becoming immobilized Via the means 164;

If it is desired to pick up two-thirds of a cube, the short stop 64 is dropped to its down.L or operative posi.- tion, being held in that position by the over-center means 84 etc; (Figure. 6\) while the long stopy remains retracted, since. the cross bar of the short stop. is ahead of the sidemembers of the long stop. Whenthe short. block stop' occupies its down' or operative positiom. the cross bar thereof lies across the tines 24 at such distance back of the free ends of the tines as to correspond substantially with the depth of the two rst block series 44 and 46 (Figure 11), thus stopping further penetration of the cube by the tines so that the last series 48 is left standing on its original support. In other words, the vertical plane of cleavage or separation in the cube lies between the block series 46 and 48. The suspension means 28, starting at its E or downhill position, will, when a lifting force is applied thereto, move uphill, this time to the 2./3 position (Figure 11), since, when the short block stop 64 was swung to its down or block-stopping position, it drew downwardly on the link 56 to rock the control shaft 106 clockwise from the position of Figure 13 to that of Figure 14, clearing the track stop 114 from the path of the cart but placing the next stop 116 in that path so as to be engaged by the cart stop 136. it should be understood at this point that the overcenter locking device 84 etc. is not only effective to retain the down position of the short stop 64 but also operates through the link 56 to releasably retain the Figure 14 position of the control shaft 106. A continuation of application of the lifting force on the suspension means then releases the swivel brake at 126 and lifts the two-thirds-full fork. The lifting point at the 2/3 position is coordinated with the center of mass of the fork and the two-thirds of the cube so that the loaded fork is again in balance and the tines are horizontal. The advantages of the level or balanced fork when two-thirds loaded are the same as those outlined for the fully loaded fork. When the tines are withdrawn from the two-thirds-of-a-cube, the suspension means will return to its E position.

If it is desired to pick up only one-third of the cube, whether separating such one-third from the front of a full cube or picking up the third left over following a two-thirds pick-up, the long stop 62 is swung down to its operative or block stopping position, the short stop 64 necessarily being brought down simultaneously or having been previously rendered operative as described above. The cross bar on the long stop traverses the tines 24 a distance back from their free ends substantially equal to a single series of blocks (Figure and the cube can be penetrated only one-third of its depth. Likewise, it what is left of the cube is only one-third or one series thereof, that series cannot move onto the fork any farther than is permitted by the operatively positioned block stop 62. Again, as the one-third-loaded fork is lifted, the suspension means 28 runs uphill, this time to its outermost or 1/3 position, since, when the long stop 62 was turned to its down or operative position, it exerted a further pull on the link 56 via the link 148 (Figure 7) and thus rotated the shaft 106 its maximum clockwise amount so that both track stops 114 and 116 were retracted from the uphill path of the cart. In other words, the stops were changed from the Figure 14 positions to those of Figure and the cart is now clear to run out to the iinal or 1/3 track stop 138, at which location the point of suspension is such that the one-third-loaded fork is in balance and the tines are horizontal. Of course, the relation of the swivel means 126 to the operation exists as before and need not be re-described.

Summary As will be seen, the suspension means is capable of occupying four different positions along the track means, depending upon the four different loading istages to which the fork is subjected, considering the empty or E stage as a loaded stage in at least one respect because of the inherent weight of the fork. Aswill also be clear, it is not the sheer weight which determines the respective points of suspension about which the fork will be balanced according to the load thereon, but this determination also involves the location of the mass of the load, or, specifically, the center of mass of the material (blocks) plus the fork. For example, and without limiting the invention thereby, the fork disclosed has an empty weight of approximately two-hundred twenty-tive pounds. A full cube weighs in the neighborhood of thirty-three hundred pounds.' The smaller sections of the cube weigh of course eleven hundred pounds per series. Stated otherwise, if the tines were allowed to penetrate a single series, such as that at 44 in Figure 10, to their full extent, the series would weigh the same as always but the center of mass would be closer to the back 22 of the fork', hence, the 1A; position shown could not be used but a new location closer to the E position would have to be set up. Although this is easily enough accomplished if all the fork has to handle is one-third cubes, the fork is then not adapted for handling other portions of a cube, including a full cube.

As indicated, the track stops 114 and 116 are adjustable via their set screws 118. An occasion for adjustment may arise in the handling of blocks of different weights; that is, concrete blocks have a weight greater than cinder blocks, for example. Some blocks have higher insulation qualities because of the predominant use of lighter materials such as vermiculite. Proper adjustment of the track stops can be achieved by trial and error and then secured. In some instances, cubes from certain sources vary as to size from the three-by-six-by-ive block cube shown here. Such cube may be only ve blocks deep and the fork must be especially designed to handle a full cube, a single series, a double series and a half-series, but such design is only a matter of simple mechanics when following the instant disclosure. The present `fork could even handle such modiiied cube without change as to the first single block series and the first two series, but some modiiication would have to be effected for the full cube and the half-series could be handled on a trial and error basis. Other variations will readily suggest themselves.

If desired, the fork may be used to pick up horizontally divided portions of the cube, as by inserting the fork tines 24 into the apertures 50 of the block layer 38 or, by approaching the cube from the side appearing at the right in Figure 3, the tines may enter the block apertures in the layer 36 etc. In general, the conditions of selfbalancing will be retained within limits because the coordination of the track and block stops is based on center of mass and not on weight alone. Thus, the arrangement is highly flexible and possesses tremendous advantages over known constructions.

Features and objects other than those categorically enumerated herein will readily occur to those versed in the art, as will many modifications of the preferred construction disclosed, all of which are available without departure from the spirit and scope of the invention.

What is claimed is:

1. A suspended loader fork for handling apertured building blocks arranged in a pattern including a front series of blocks supported in a horizontal plane with their apertures extending fore-and-aft and at least a rear series of similar blocks supported in the same plane with their apertures fore-and-aft and alined respectively with the apertures in the blocks in the front series, said fork comprising: a generally upright rigid frame means having upper and lower parts; a plurality of spaced apart horizontally coplanar tines rigid on the lower part of said frame means and extending therefrom to free outer ends adapted to penetrate both series of blocks via said alined apertures; track means rigid on the upper part of said frame means and inclining upwardly and outwardly therefrom in overhanging relation to the tines; suspension means carried by the track and biased to a downhill position thereon substantially directly over the center of mass of the empty fork, said suspension means being movable uphill by a lifting force applied thereto when the fork is loaded; a lirst track stop on the fork having an operative position limiting uphill movement of the suspension means to a first location substantially directly above the center gemss of mass of the fork when loaded with both series: of blocks, said first track stop being movable to` an: inoperative position enabling further uphill movement of said suspension means; ablock stop` on the fork and selectively settable between a first position enabling the tines to penetrateA both seriesy of blocks and a second position enabling the tines to penetrate only they front series of blocks; means interconnecting the block stop and the track stop for incurring the operative and inoperative positions of said track stop respectively according tothe first and second positions of said block stop; and a second track stop on the track means uphill from the first track stop for limiting uphill movement of the suspension means to ay second location substantially directly over the center of mass of the fork when loaded withv only said front series of blocks.

2. The invention defined in claim l, in which: the

suspension means includes a roller-mounted element mov-v able along the track; the first track stop includes a shaft parallel to the track means and' rockably supported thereby and a stop arm having a rigid mounting on said shaft, said shaft being rockable according to the positionof the block stop to move said arm selectively into and outof the uphill path of said roller-mounted element.

3. The invention defined in claim 2, in which: said rigid mounting of the arm on the shaft includes provision for selective adjustment of the arm along the shaft to adjust the location at whiclr said arm stops the rollermounted element.

4. The invention defined in claim l, in which: the block stop comprises a member pivoted to the fork on an axis transverse to and generally at the level of the tines and adjacent to the frame means for swinging upwardly to said first position and downwardly to said second position, said member having its end portion remote from said axis positionable in said second position at a distance back from the free end of at least one tine substantially equal to the fore-and-aft dimension ofthe front series of blocks.

5. The invention defined in claim 4, including: releasable means for retaining the pivoted member in at least its first position.

6. The invention defined in claim l, in which: the first track stop includes a shaft parallel to the track means and rockably supported thereby and a stop arm having a rigid mounting on said shaft, said shaft being rockable according to the position ofthe block stop to move said arm selectively into and out of the uphill path of said suspension means.

7. The invention defined in claim 6, in which: said rigid mounting of the arm on the shaft includes provision for selective adjustment of the arm .along the shaft to adjust the location at which said arm stops the suspension means.

8. A suspended loader fork for handling apertured building blocks arranged in a pattern including a front series of blocks supported in a horizontal plane with their apertures extending fore-and-aft and at least a rear series of similar 'blocks supported in the same plane with their apertures fore-and-aft and alined respectively with the apertures in the blocks in the front series, said fork comprising: a generally upright rigid frame means having upper and lower parts; a plurality of spaced apart hor1- zontally coplanar tines rigid on the lower part of said frame means and extending therefrom to free outer ends adapted to penetrate both series of blocks via said alined apertures; track means rigid on the upper part of sald frame means and extending outwardly therefrom in overhanging relation to the tines; suspension means carried by the track and biased to an inward positlon thereon adjacent to the frame means and substantlally directly over the center of mass of the empty fork; means causing said suspension means to move outwardly on said track means to receive a lifting force when the fork. 1s. loaded; a first track stop on the fork having an operative 4iti l position limiting outward movement of the suspension means to a rstl location substantially directly above the center of massv of the fork when loaded with both series of blocks said first track stop being movable to an inoperative position enabling further outward movement of said suspension means; a block stop on the fork and selectively settable between a first position enabling the tines to penetrate both. series of blocks and a second position enabling the tines to penetrate only the front series of blocks; means interconnecting the block stop and the track stop for incurring the operative and inoperative positions of said track stop respectively according to the first and second positions ofsaid block stop; and a second track stop on the track means outwardly from the first track stop for limiting outward movement of the sus;- pension means to a second location substantially directly over the center of mass of the fork when loaded with only said front series of blocks.

9. The invention defined in claim 8, in which: the' suspension means includes a first part riding the track, a second part connectedv to the first part on an upright swivel axis and adapted to receive a lifting force, and means interengageable between said first and second parts for limiting swiveling of said second part relative tothe firsty part while said fork is empty and enabling swiveling when the fork is loaded.

101. A suspended loader fork comprising: a generally upright rigid' frame means; tines rigid on the lower part of said. frame means and extending therefrom to free outer ends adapted to receive a load thereon; track means rigid on the upper part of said frame means and inclining upwardly and outwardly therefrom in overhanging relation to the tines; suspension means carried by the track andi biased to a downhill position thereon substantially directly over the center of mass of the empty fork,l said suspension means being movable uphill by a lifting force applied thereto when the fork is loaded; a track stop limiting uphill movement of the suspension means; and said suspension means including a rst part riding the track, a second part connected to said first part on an4 upright swivel axis and shiftable vertically within limits along said axis relative to said first part, means biasing the second part downwardly into engagement with the first part for restricting swiveling thereof, and meanson the second part for receiving a lifting force when. the fork is loaded so as to compress said biasing means and remove the restriction on said swiveling.

ll. A suspendedyloader fork for handling apertured building blocksV arranged as .a front series of horizontally coplanar blocks having their apertures fore-and-aft and a second and a third series of similar blocks consecutiveiy behind and having their apertures alined fore-and-aft respectively with tho-se in the front series, said fork comprising: a generally upright rigid frame means; tines rigid on the lower part of said frame means and extending therefrom to free outer ends and of sufficient length to penetrate all three series of blocks via said alined apertures; track means rigid` on the upper part of said frame means and extending outwardly therefrom in overhanging relation to the tines; suspension means carried by the track and having .an inward position thereof adjacent to the frame means and substantially directly over the center of mass of the empty fork; means causing saidsuspension to move outwardly on said track means to receive a lifting force when the fork is loaded; .a first track stop projectible to limit outward movement of the suspension means to a first location substantially directly above the center of mass of the fork when loaded with all three series of blocks and retractable to enable further outward movement of said suspension means; a second track stop spaced outwardly beyond said first track stop and projectible to limit said further outward movement of the suspension means to a second location substantially directly over the center of mass of the fork when loaded with the front and second series of blocks and retractable to permit still further outward movement of the suspension means; first and second block stops normally retracted on the fork to enable the tines to penetrate all three series of blocks, said first block stop being settable in an operating position enabling the tines to penetrate only the front and second series of blocks and said second block stop being settable in an operating position enabling the tines to penetrate only the front series of blocks; means interconnecting the block stops and the first and second track stops for projecting the first track stop when both stops are retracted, for retracting the first track stop and projecting the second track stop when the first block stop is in its operating position and for retracting both track stops when the second block stop is in its operating position whereby the suspension means is movable outwardly beyond both track stops when the fork is loaded with only the front series of blocks; and a third track stop outwardly beyond the second track stop for limiting outward movement of the suspension means to a third location substantially directly over the center of mass of the fork when loaded with only the front series of blocks.

l2. The invention defined in claim l1, in which: the first and second track stops include a shaft parallel to and rockably carried by the track means and first and second stop arms secured to said shaft in axially and angularly spaced apart relation and adapted selectively to project into the path of outward movement of the suspension means; means biasing the shaft to a position inV which the first stop arm projects into said path to determine said first location; and the interconnecting means is operative to rock the shaft sequentially to first remove the first stop arm and place the second stop arm in said path and then to remove both stop arms from said path respectively according to the operating positions of the first and second block stops.

13. A suspended loader element, comprising: a generally upright back having upper and lower parts; elongated material-carrying means rigidly attached to said lower part and extending forwardly and generally horizontally therefrom to a free front end portion adapted to penetrate stacked material of a nature capable of separation generally at upright planes transverse to the length of said carrying means so that the extent of material penetration by said means determines the location of the center of mass of the material load on said means; track means rigid on the upper part of said back and extending uphill and forwardly therefrom in overhanging relation to the carrying means; suspension means carried by the track means t and biased to a downhill position substantially directly above the center of mass of the element when empty, said suspension means tending to run uphill on the track means in response to a lifting force applied thereto when said element is loaded; stop means selectively settable on t the element in any one of a plurality of positions for engaging the material to control the extent of material penetration by the carrying means and thereby to selectively determine for each position a center of mass for the material-loaded element; and track control means operative in response to setting of said stop means in each position to limit uphill travel of the suspension means to a location substantially directly above the selected center of mass of the material-loaded element.

14. A suspended loaderr element, comprising: a generally upright back having upper and lower parts, elongated material-carrying means rigidly attached to said lower part and extending forwardly and generally horizontally therefrom to a free front end po-rtion adapted to penetrate stacked material of a nature capable of separation generally at upright planes transverse to the length of said carrying means so that the extent of material penetration by said means determines the location of the center of mass of the material load on said means; track means rigid on the upper part of said back and extending forwardly therefrom in overhanging relation to the carrying means; suspension means carried by the track means and biased to a back-proximate position substantially directly above the center of mass of the element when empty; means causing said suspension means to move forwardly on the track means to receive a lifting force when said element is loaded; stop means selectively settable on the element in any one of a plurality of positions for engaging the material to control the extent of material penetration by thc carrying means and thereby to selectively determine for each position a center of mass for the material-loaded element; and track control means operative in response to setting of said stop means in cach position to limit forwardtravel of the suspension means to a location substantially directly above the selected center of mass of the material-loaded element.

15. A suspended loader element, comprising: a generally upright back having upper and lower parts; elongated material-carrying means rigidly attached to said lower part and extending forwardly and generally horizontally therefrom to a free front end portion adapted to penctrate stacked material of a nature capable of separation generally at upright planes transverse to the length of said carrying means so that the extent of material penetration by said means determines the location of the center of mass of the material load on said means; track means rigid on the upper part of said back and extending forwardly therefrom in overhanging relation to the carrying means; suspension means carried by the track means and biased to a back-proximate position substantially balancing the empty element in suspension from said suspension means; means causing said suspension means to move outwardly along the track means as varying load masses are applied to the element according to the amount of material penetration of material by the carrying means; and means operative responsively to such load masses for controlling outward movement of the suspension means to locations respectively substantially balancing the suspended loaded element according to each different load mass thereon.

16. A load-handling device, comprising: a generally uprightrigid frame having upper and lower ends; a generally horizontal load-receiving element rigidly joined to the lower end of the frame and extending outwardly therefrom to a free outer end portion adapted to enter and support load material; a rigid track joined to the upper end of the frame and extending outwardly therefrom in overhanging relation to the element; suspension means movable selectively inwardly and outwardly along the track and having an inward starting position; means for causing the suspension means to move outwardly on the track when said device is loaded; a control shaft rockably carried by the track on an axis parallel thereto; a first stop arm secured to the shaft in outwardly spaced relation to the frame and adapted to project into or be cleared from the path of outward movement of the suspension means; means biasing the shaft to a normal position in which said first stop arm is projected; a second stop arm secured to the shaft in outwardly spaced relation to the first stop arm and spaced angularly about said shaft relative to said first arm so as to lie clear of the path of outward movement of the suspension means in the normal position of the shaft; a pivot at the junction of the frame and element and transverse to the element; a short stop mounted on said pivot for swinging between an upright retracted position to an operating position of extension relative to the element to dispose its outer end in Said latter position at a point spaced inwardly a certain distance from the free outer end of said element; link means interconnecting the short stop and the control shaft for incurring the normal position of the shaft in response to the retracted position of the short stop and for rocking said shaft to clear the first arm and project the second arm when said short stop is swung to its extension position; a long stop mounted on said pivot for swinging between an upright retracted position and a position of extension relative to the element to dispose its free end at a point spaced inwardly from the free outer end of said element a distance less than the aforesaid distance of the short stop; and lost-motion means connecting the long stop to the link means and enabling swinging movement of the short stop while the long stop is in its retracted position and for incurring further rocking of the control shaft by the long stop in its position of extension so as to clear both stop arms from the path of outward movement of the suspension means.

17. The invention defined in claim 16, including oneway means interconnecting the long and short stops for incurring movement of both stops to their respective positions of extension upon movement of the long stop to its position of extension but permitting independent movement of the short stop in both directions.

18. A suspended loader element of the class described, comprising: ya generally upright back frame; load-supporting means connected to and extending generally horizontally from a lower portion of said frame; a track rigidly connected to an upper portion of said frame and extending in'overhanding relation to said load-supporting means, said track inclining upwardly and outwardly from said frame; suspension means riding the track and biased to a downhill position adjacent to the back frame and substantially directly over the center of mass of said element when empty, said suspension means being movable uphill on the track when subjected to a lifting force when the element is loaded; and stop means on the element limiting uphill movement of the suspension means to a position substantially directly above the center of mass of the loaded element.

19. A suspended loader element of the class described, comprising: a generally upright back frame; load-support-ing means connected to and extending generally horizontally from a lower portion of said frame; a cantilever track rigidly connected to an upper portion of said frame and extending in overhanging relation to said load-supporting means, said track inclining upwardly and outwardly from said frame; a track follower on the track and movable between a downhill position adjacent to the back frame and an uphill position remote from said back frame;

means on the element limiting downhill movement of the follower to establish said downhill position substantially directly over the center of mass of said element when empty; means on the element -yi'eldingly biasing the follower to said downhill position; and means on the element limiting uphill movement of the follower to establish said uphill position substantially directly above the center of mass of the loaded element.

20. A suspended loader fork comprising: a generally upright back frame having a lower end and an upper end; a fork element joined rigidly to said lower end and extending generally horizontally outwardly therefrom to a free outer end portion adapted to penetrate load material; first stop means selectively positionable on the loader fork between an inactive position clear of load material to be penetrated by the fork element and a stop position short of the free outer end portion of said element to limit penetration of the material by said element to a relatively small amount; and second stop means selectively positionable on the loader fork between an inactive position clear of penetrated material and a stop position intermediate the back frame and the active position of the rst stop means to enable penetration of load material by said element to a greater extent than permitted by the actively positioned first stop means but less than full penetration.

21. The invention dened in claim 20, including: means mounting the first and second stop means for incurring their active positions together and enabling return of the first stop means alone to its inactive position while the second stop means retains its active position.

References Cited in the le of this patent UNITED STATES -PATENTS 

